Investigation and design of millimeter-wave switches in 28 nm CMOS technology

Nowadays, considerable effort is being put into designing integrated circuits that operate at increasingly higher frequencies for use in high data-rate wireless communication systems or very accurate sensing with radars. The continuous improvement in silicon manufacturing technology allows to build analog circuits based on MOSFETs with channel lengths as short as tens of nm. Thus, standard bulk CMOS technology is again becoming an attractive solution for new generations of RF and millimeter-wave circuits, since it offers performance comparable to advanced technologies based on new materials, but with better integrability and at a lower production cost. This work investigates the performance of millimeter-wave switches fabricated in a 28 nm bulk CMOS technology. The switches are designed to find application in a MIMO radar system operating at 60 GHz, where they can be used to realize Time Division Multiplexing functions or to implement step-attenuators. In detail, a design procedure is proposed here to find the sizes of the MOSFETs that optimize the insertion loss of the millimeter-wave switches. The procedure is applied to design three different switch topologies: the resonant series switch, the λ/4 switch and the lumped λ/4 switch. A possible layout is reported for each topology and the simulated performance achieves the targets of at least 15 dB return loss, 10 dB isolation, and shows about 2 dB insertion loss for all the three implementations. In particular, the resonant series switch exhibits the lowest insertion loss (1.7 dB) and highest input 1-dB compression point (12 dBm) over the whole band of interest and is the simplest and most compact solution. This work has been carried out in collaboration with Infineon Technologies Austria AG.